Vane type vacuum pump

ABSTRACT

A vane type vacuum pump has a discharge port for discharging suctioned air, and a reed valve part that opens and closes the discharge port. The reed valve part includes a first reed valve that is installed to cover the opening of the discharge port, and a second reed valve that is superposed with the first reed valve. The first reed valve and the second reed valve have different resonance frequencies by having different thicknesses.

BACKGROUND OF THE INVENTION

The present invention relates to a vane type vacuum pump that inhales a gas and discharges the gas from a discharge port.

A conventional vane type vacuum pump is described in Japanese Laid-Open Patent Publication No. 2012-057622. The vane type vacuum pump described in Japanese Laid-Open Patent Publication No. 2012-057622 includes a reed valve that is installed at a discharge port. The discharge port is opened and closed by deflecting the reed valve by a discharge pressure of the gas. In Japanese Laid-Open Patent Publication No. 2012-057622, it is also described that the reed valve is formed with a leaf spring which includes a single plate or a laminated plate.

In the above vane type vacuum pump, the reed valve sometimes resonates due to disturbance of a flow of the gas that is discharged from the discharge port. When the reed valve resonates, a pulsation occurs in the gas discharged from the discharge port. Then, by the pulsation of the gas, a pressure variation occurs in the installation space of the vane type vacuum pump. A wall surface of the installation space vibrates due to the pressure variation, and vibration energy of the wall surface vibration is radiated to an outer side as sound, and abnormal noise occurs.

SUMMARY OF THE INVENTION

The vane type vacuum pump includes a first reed valve that is installed at the discharge port, and a second reed valve that is superposed with the first reed valve and has a resonance frequency which is different from that of the first reed valve.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a vane type vacuum pump according to a first embodiment of the present invention;

FIG. 2 is a perspective view of a reed valve part;

FIG. 3 is an exploded perspective view of the reed valve part;

FIG. 4A is a sectional view showing a state that the reed valve part is closed;

FIG. 4B is a sectional view showing a state that the reed valve part is opened;

FIG. 5A is a plan view of a first reed valve that configures a reed valve part of a vane type vacuum pump according to a second embodiment of the present invention;

FIG. 5B is a plan view of a second reed valve that configures the reed valve part;

FIG. 6A is a plan view of a first reed valve that configures a reed valve part of a vane type vacuum pump according to another example;

FIG. 6B is a plan view of a second reed valve that configures the reed valve part;

FIG. 7A is a plan view of a first reed valve that configures a reed valve part of a vane type vacuum pump according to another example;

FIG. 7B is a plan view of the second reed valve that configures the reed valve part;

FIG. 8A is a plan view of a first reed valve that configures a reed valve part of a vane type vacuum pump according to a third embodiment of the present invention; and

FIG. 8B is a plan view of a second reed valve that configures the reed valve part.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

Hereinafter, a vane type vacuum pump according to a first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4B.

The vane type vacuum pump is installed inside a cylinder head of an engine in a state that a lower portion is soaked in oil. The vane type vacuum pump is coupled to a camshaft. When the camshaft has rotated, the vane type vacuum pump suctions air from a negative pressure actuator such as a brake booster, and discharges the air within the cylinder head.

As shown in FIG. 1, the vane type vacuum pump has a discharge port 10 for discharging the suctioned air, and a reed valve part 11 that opens and closes the discharge port 10. In a state that the vane type vacuum pump is installed within the cylinder head cover, the discharge port 10 is laid out at a slightly higher side than the liquid surface of the oil.

As shown in FIGS. 2 and 3, the reed valve part 11 includes a first reed valve 12, a second reed valve 13, and a stopper member 14. At right side end parts of the first reed valve 12, the second reed valve 13, and the stopper member 14, through-holes 12 c, 13 c, and 14 c are formed, respectively. The first reed valve 12, the second reed valve 13, and the stopper member 14 are superposed with each other in this order from the discharge port 10 side. At the lateral side of the discharge port 10, a screw hole 15 is formed. The first reed valve 12, the second reed valve 13, and the stopper member 14 are fitted to a pump body 17, by fastening a bolt 16 that has pierced through the through-holes 12 c, 13 c, and 14 c, with the screw hole 15.

The first reed valve 12 and the second reed valve 13 have the same materials and the same planar shapes, but have different thicknesses. In FIG. 3, the thickness of the second reed valve 13 is shown larger than the thickness of the first reed valve 12. However, the thickness of the first reed valve 12 may be larger than the thickness of the second reed valve 13.

The first reed valve 12 and the second reed valve 13 include fixed portions 12 a and 13 a, and valve body portions 12 b and 12 b. The fixed portions 12 a and 13 a are portions that are fixed to the pump body 17 with the bolt 16. The valve body portions 12 b and 13 b are elastically deformable portions in the first reed valve 12 and the second reed valve 13. The valve body portions 12 b and 13 b have shapes and sizes that cover a whole opening of the discharge port 10. The valve body portion 12 b of the first reed valve 12 is brought into contact with a valve seat 18 that is provided at the peripheral edge of the opening of the discharge port 10. The first reed valve 12 and the second reed valve 13 are superposed with each other in a state that the valve body portions 12 b and 13 b are slide-contacted with each other.

The stopper member 14 is made of metal, and has a larger thickness than the thicknesses of the first reed valve 12 and the second reed valve 13. The stopper member 14 has a first end part that is fixed to the bolt 16, and a second end part located opposite to the first end part. The stopper member 14 is curved so as to be separated from the discharge port 10 as the stopper member 14 proceeds from the first end part to the second end part.

An operation of the reed valve part 11 of the vane type vacuum pump will be described with reference to FIGS. 4A and 4B.

During the operation of the vane type vacuum pump, air is intermittently discharged from the discharge port 10. The reed valve part 11 operates to open the discharge port 10 during discharge of the air, and close the discharge port 10 during non-discharge of the air.

In the state shown in FIG. 4A, the valve body portion 12 b of the first reed valve 12 is in contact with the valve seat 18, and the opening of the discharge port 10 is closed. As shown in FIG. 4B, when the air starts being discharged from the discharge port 10, the valve body portion 12 b of the first reed valve 12 is curved and deflected and the valve body portion 13 b of the second reed valve 13 that is brought into contact with the valve body portion 12 b is also curved and deflected, by the pressure of the air. Accordingly, the valve body portion 12 b of the first reed valve 12 is separated from the valve seat 18, and the discharge port 10 is opened.

When the inverse number of the cycle of opening and closing the discharge port 10 becomes close to the intrinsic vibration frequencies of the first reed valve 12 and the second reed valve 13, the first reed valve 12 and the second reed valve 13 resonate. When the first reed valve 12 and the second reed valve 13 resonate simultaneously, a pulsation occurs in the air that is discharged from the discharge port 10. Then, a pressure variation occurs in the space within the cylinder head cover in which the vane type vacuum pump is installed. The wall surface of the cylinder head cover vibrates due to the pressure variation, the vibration energy is radiated to the outer side as sound, and abnormal noise occurs.

In this respect, according to the vane type vacuum pump of the first embodiment, the first reed valve 12 and the second reed valve 13 have different resonance frequencies because they have different thicknesses. Therefore, the first reed valve 12 and the second reed valve 13 do not resonate simultaneously. Accordingly, even when one of the first reed valve 12 and the second reed valve 13 resonates, the vibration is suppressed by the other reed valve that does not resonate. Consequently, a vibration amplitude during resonance becomes smaller.

Further, at the time of opening and closing the discharge port 10, a relative sliding occurs between contact surfaces of the first reed valve 12 and the second reed valve 13 that are superposed with each other. Therefore, according to the vane type vacuum pump of the first embodiment, vibrations of the first reed valve 12 and the second reed valve 13 are attenuated by the friction between the contact surfaces due to relative sliding.

The stopper member 14 regulates the opening of the first reed valve 12 and the second reed valve 13 not to exceed a constant amount of opening. Therefore, even when a discharge pressure of the air from the discharge port 10 has become excessively large, excessive opening of the first reed valve 12 and the second reed valve 13 can be regulated.

According to the vane type vacuum pump of the first embodiment, the following advantages can be obtained.

(1) According to the vane type vacuum pump, the first reed valve and the second reed valve are deflected by the discharge pressure of the gas so that the discharge port is opened and closed. When the inverse number of the cycle of opening and closing the discharge port becomes close to the resonance frequency of the first reed valve and the second reed valve, the first reed valve and the second reed valve resonate. In this respect, according to the vane type vacuum pump of the first embodiment, the reed valve that opens and closes the discharge port 10 is configured as follows. That is, the reed valve is configured by superposing the first reed valve 12 and the second reed valve 13 that have different resonance frequencies. According to this configuration, because the first reed valve 12 and the second reed valve 13 have different resonance frequencies, the first reed valve 12 and the second reed valve 13 do not resonate simultaneously. Accordingly, even when one of the first reed valve 12 and the second reed valve 13 resonates, the vibration is regulated by the other reed valve that does not resonate. As a result, resonance of the reed valve that becomes the cause of the abnormal noise can be suppressed.

(2) Therefore, vibrations of the first reed valve 12 and the second reed valve 13 are attenuated by friction between the contact surfaces of the first reed valve 12 and the second reed valve 13. As a result, resonance of the reed valves can be suppressed.

(3) At the outer side of the first reed valve 12 and the second reed valve 13, the stopper member 14 is provided to limit a valve open amount of the first reed valve 12 and the second reed valve 13. Therefore, it is possible to suppress excessive deformation of the first reed valve 12 and the second reed valve 13 and remaining of the deformation in the reed valve.

(4) Simply differentiating the thicknesses of the first reed valve 12 and the second reed valve 13 makes it possible to easily differentiate the resonance frequencies of the first reed valve 12 and the second reed valve 13. For example, in the case of stamping the first reed valve 12 and the second reed valve 13, it is possible to manufacture the first reed valve 12 and the second reed valve 13 by using the same stamping mold, by simply changing the thicknesses of metal materials.

Second Embodiment

Next, a vane type vacuum pump according to a second embodiment of the present invention will be described with reference to FIGS. 5A to 7B. In describing the second embodiment, configurations that are common to the first embodiment are attached with the same symbols, and their detailed descriptions will be omitted.

As shown in FIGS. 5A and 5B, the vane type vacuum pump of the second embodiment uses two reed valves. A first reed valve 21 shown in FIG. 5A is installed so as to be in contact with the valve seat 18 surrounding the discharge port 10 shown in FIG. 2. A second reed valve 22 shown in FIG. 5B is superposed on the first reed valve 21 in a state that valve body portions of the first and second reed valves 21 and 22 can be slide-contacted with each other. Although the first reed valve 21 and the second reed valve 22 have the same materials and the same thicknesses, the first reed valve 21 and the second reed valve 22 have different planar shapes.

In the case of FIGS. 5A and 5B, the valve body portion of the second reed valve 22 is formed smaller than the valve body portion of the first reed valve 21.

In the second embodiment, the first reed valve 21 and the second reed valve 22 also have different resonance frequencies by having different planar shapes. Therefore, the first reed valve 21 and the second reed valve 22 do not resonate simultaneously, and resonance of the reed valve that becomes the cause of abnormal noise can be suppressed. Consequently, the advantages described in the above (1) to (3) can be also obtained by the vane type vacuum pump of the second embodiment.

In the example shown in FIGS. 5A and 5B, by setting the valve body portion of the second reed valve 22 to be smaller than the valve body portion of the first reed valve 21, shapes of both reed valves have been differentiated. However, shapes of both reed valves may be differentiated by the following mode.

As shown in FIGS. 6A and 6B, by setting the valve body portion of a second reed valve 24 to be larger than the valve body portion of a first reed valve 23, resonance frequencies of both reed valves may be differentiated.

As shown in FIGS. 7A and 7B, by forming a hole 27 in one of valve body portions of a first reed valve 25 and a second reed valve 26, resonance frequencies of both reed valves may be differentiated. In FIG. 7B, the hole 27 is formed on the second reed valve 26. Further, by forming holes on both the first and second reed valves and by differentiating shapes, sizes, and numbers of the holes, resonance frequencies of both reed valves may be differentiated.

Third Embodiment

Next, a vane type vacuum pump according to a third embodiment of the present invention will be described with reference to FIGS. 8A and 8B. In describing the third embodiment, configurations that are common to the above embodiments are attached with the same symbols, and their detailed descriptions will be omitted.

As shown in FIGS. 8A and 8B, the vane type vacuum pump of the third embodiment uses two reed valves. A first reed valve 28 shown in FIG. 8A is installed so as to be in contact with the valve seat 18 surrounding the discharge port 10. A second reed valve 29 shown in FIG. 8B is superposed on the first reed valve 28 in a state that valve body portions of the first and second reed valves 21 and 22 can be slide-contacted with each other. Although the first reed valve 28 and the second reed valve 29 have the same sizes and the same shapes, these reed valves are respectively formed with different materials.

In the third embodiment, the first reed valve 28 and the second reed valve 29 also have different resonance frequencies by being formed with different materials. Therefore, the first reed valve 28 and the second reed valve 29 do not resonate simultaneously, and resonance of the reed valve that becomes the cause of abnormal noise can be suppressed. Consequently, the advantages described in the above (1) to (3) can be also obtained by the vane type vacuum pump of the third embodiment.

The above embodiment may be changed as follows.

Shapes of the first and second reed valves and the stopper member may be changed to match the shape of the discharge port of the vane type vacuum pump that is applied.

The stopper member 14 may be omitted.

By differentiating two or all of thicknesses, shapes, and materials of the first and second reed valves, resonance frequencies of both reed valves may be differentiated.

In the above embodiments, although the first and second reed valves are different members, both reed valves may be integrally formed when the valve body portions can be slide-contacted with each other. For example, by folding one plate material into two portions, the reed valve may be configured such that two valve body portions are superposed to be able to be slide-contacted with each other. 

1. A vane type vacuum pump that inhales a gas and discharges the gas from a discharge port, the vane type vacuum pump comprising: a first reed valve that is installed at the discharge port; and a second reed valve that is superposed with the first reed valve and has a resonance frequency which is different from that of the first reed valve.
 2. The vane type vacuum pump according to claim 1, wherein the first reed valve and the second reed valve have different thicknesses.
 3. The vane type vacuum pump according to claim 1, wherein the first reed valve and the second reed valve have different shapes.
 4. The vane type vacuum pump according to claim 1, wherein the first reed valve and the second reed valve are formed with different materials.
 5. The vane type vacuum pump according to claim 1, further comprising: a stopper member that is provided at an outer side of the first reed valve and the second reed valve to limit a valve open amount of the first reed valve and the second reed valve. 